Progressive spectacle ophthalmic lenses are worn and widely used for correcting many different types of vision deficiencies such as near-sightedness (myopia) or far-sightedness (hypermetropia), astigmatism, and defects in near-range vision usually associated with aging (presbyopia).
Ophthalmologists or optometrists routinely improve the visual acuity by correcting refractive errors in terms of sphere, cylinder, axis and addition.